ProTec DMDR 20
The Raycap ProTec DMDR 20 is a Class III / Type 3 fine protection device that intervenes where Class I and Class II surge arresters are insufficient to protect sensitive electronic equipment. It features a pluggable module structure for DIN rail mounting; each pole has a hybrid design consisting of a high-performance varistor and a high-energy encapsulated gas discharge tube (GDT). It is used in AC and DC systems with 24 V, 48 V, 60 V, and 120 V versions.
In a cascaded lightning protection chain, Class I and Class II surge arresters handle high-energy surges. However, the remaining residual voltage after these stages can still be too high for sensitive electronic boards. Additionally, low-level but frequently repeated surges occurring within the facility—such as the activation of large equipment, inductive loads, motor switching, or industrial system failures—are not suppressed at all, as they fall below the threshold of Class I/II devices.
ProTec DMDR 20 fills this gap. Devices in the IEC Class III / EN Type 3 classification are designed for the protection of sensitive electronic installations within Zone 2-3 (LPZ 2-3) according to IEC 62305—that is, as the final stage, in the immediate vicinity of the equipment.
The technical distinguishing feature of the device is its hybrid design: each pole contains a high-performance varistor (MOV) and also a high-energy encapsulated gas discharge tube (GDT); both have separate thermal disconnector mechanisms. This combination merges the fast response of the varistor with the high energy handling and leakage-current-free operation of the GDT.
The device provides protection in L-N, L-PE, and N-PE directions. The response time is < 25 ns in the L-N direction and < 100 ns in the L-PE / N-PE direction. The protection level (Up) ranges from 250 V to 1100 V in the L-N direction depending on the model—low residual voltage values expected from Class III devices.
Thanks to its pluggable module structure, an end-of-life module can be replaced on-site without disconnecting system wiring. The green LED on the front indicates the operating status. The device is 1 TE / 18 mm wide—occupying minimal space in sub-distribution boards.
The series is available in four voltage options: 24, 48, 60, and 120 (AC/DC). The 24 V model is also UL certified and carries DC SPD Type 4CA classification. The products comply with IEC 61643-11:2011, EN 61643-11:2012+A11:2018, and UL 1449 5th Edition standards.
- IEC Class III / EN Type 3 SPD — fine (final stage) protection
- DC SPD Type 4CA classification
- Hybrid design: high-performance varistor + high-energy encapsulated GDT per pole
- Separate thermal disconnector mechanisms for varistor and GDT
- Pluggable module — on-site replacement without disconnecting wiring
- Protection mode: L-PE, N-PE, L-N
- Network system: TN-S
- Zone 2-3 (LPZ 2-3) protection according to IEC 62305
- Fast response time: < 25 ns (L-N) / < 100 ns (L-PE, N-PE)
- Four voltage options: 24 / 48 / 60 / 120 (AC/DC)
- Operating status indicator: green LED
- Thermal protection
- 35 mm DIN rail mounting (EN 60715)
- Compact size: 1 TE / 18 mm, 96 g
- Housing: UL 94 V-0 flame retardant thermoplastic
- Protection class: IP 20 (embedded)
- Standards: IEC 61643-11:2011, EN 61643-11:2012+A11:2018, UL 1449 5th Edition
Electrical values (IEC)
| 24* | 48 | 60 | 120 | |
|---|---|---|---|---|
| Nominal AC/DC voltage Uo | 17 V / 17 V | 34 V / 48 V | 43 V / 60 V | 85 V / 120 V |
| Max. continuous operating voltage (AC/DC) Uc | 24 V / 34 V | 48 V / 60 V | 60 V / 75 V | 120 V / 150 V |
| Open circuit voltage Uoc (1.2/50 µs) | 2.4 kV | 2.4 kV | 6 kV | 6 kV |
| Short-circuit current Icw (8/20 µs) | 1.2 kA | 1.2 kA | 3 kA | 3 kA |
| Max. discharge current Imax (8/20 µs) | 2 kA | 2 kA | 4 kA | 4 kA |
| Protection level Up (L-N) | < 250 V | < 500 V | < 600 V | < 1100 V |
| Protection level Up (L-PE / N-PE) | < 700 V | < 800 V | < 850 V | < 1200 V |
| Response time tA (L-N) | < 25 ns | < 25 ns | < 25 ns | < 25 ns |
| Response time tA (L-PE / N-PE) | < 100 ns | < 100 ns | < 100 ns | < 100 ns |
| TOV withstand 5 s (AC) UT | 115 V | 148 V | 163 V | 225 V |
| Overcurrent protection (max.) | 32 A gG | 32 A gG | 32 A gG | 32 A gG |
| Overcurrent protection (min.) | 8 A gG | 8 A gG | 16 A gG | 16 A gG |
| Short-circuit withstand ISCCR (AC) | 2 kA | 2 kA | 2 kA | 2 kA |
| Number of ports | 1 | 1 | 1 | 1 |
*UL certified model
Electrical values (UL — 24 V model only)
| 24 | |
|---|---|
| Max. continuous operating voltage (AC) MCOV | 24 V |
| Max. continuous operating voltage (DC) (+)-(-) Vdcmcov | 34 V |
| Max. continuous operating voltage (DC) (+/-)-(G) | 17 V |
| Measured limiting voltage (L-N)/(+)-(-) MLV | 190 V / 230 V |
| Measured limiting voltage (L/N-G)/(+/-)-(G) | 580 V / 540 V |
| In (8/20 µs) | 1 kA |
Mechanical & Environmental
- Operating temperature: -40 °C … +85 °C | Humidity: 5–95%
- Terminal tightening torque: 0.5 Nm
- Conductor cross-section (max.): 6 mm² (solid/stranded) / 4 mm² (flexible)
- DIN 43880 size: 1 TE / 18 mm
- Weight: 96 g (replacement module: 32 g)
ProTec DMDR 20 is used as the final stage of the cascaded protection chain, near the equipment to be protected:
- Sub-distribution boards — Final stage fine protection
- Sensitive electronic installations — within IEC 62305 Zone 2-3 (LPZ 2-3)
- Control and automation panels — Protection of PLCs, controllers, and I/O cards
- Third stage after Class I / Class II — Reduction of residual voltage
- Facilities with motors and inductive loads — Internal surges due to switching
- Low-voltage DC supply lines — 24 V, 48 V, 60 V DC control supplies
- Telecom and communication cabinets — 48 V DC systems
- Industrial machine panels — Against surges due to system failure
- Measurement and instrumentation systems — Sensitive measurement electronics
- TN-S network systems — Defined network structure
- Service continuity critical points — Fast replacement with pluggable module
